CVE-2020-28935
NLnet Labs Unbound/NSD Symlink PID File Vulnerability
Description
NLnet Labs Unbound, up to and including version 1.12.0, and NLnet Labs NSD, up to and including version 4.3.3, contain a local vulnerability that would allow for a local symlink attack. When writing the PID file, Unbound and NSD create the file if it is not there, or open an existing file for writing. In case the file was already present, they would follow symlinks if the file happened to be a symlink instead of a regular file. An additional chown of the file would then take place after it was written, making the user Unbound/NSD is supposed to run as the new owner of the file. If an attacker has local access to the user Unbound/NSD runs as, she could create a symlink in place of the PID file pointing to a file that she would like to erase. If then Unbound/NSD is killed and the PID file is not cleared, upon restarting with root privileges, Unbound/NSD will rewrite any file pointed at by the symlink. This is a local vulnerability that could create a Denial of Service of the system Unbound/NSD is running on. It requires an attacker having access to the limited permission user Unbound/NSD runs as and point through the symlink to a critical file on the system.
INFO
Published Date :
Dec. 7, 2020, 10:15 p.m.
Last Modified :
March 29, 2023, 3:15 p.m.
Source :
[email protected]
Remotely Exploitable :
No
Impact Score :
3.6
Exploitability Score :
1.8
Affected Products
The following products are affected by CVE-2020-28935
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2020-28935.
| URL | Resource |
|---|---|
| https://lists.debian.org/debian-lts-announce/2021/02/msg00017.html | Mailing List Third Party Advisory |
| https://lists.debian.org/debian-lts-announce/2023/03/msg00024.html | |
| https://security.gentoo.org/glsa/202101-38 | Third Party Advisory |
| https://www.nlnetlabs.nl/downloads/nsd/CVE-2020-28935.txt | Vendor Advisory |
| https://www.nlnetlabs.nl/downloads/unbound/CVE-2020-28935.txt | Vendor Advisory |
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2020-28935 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2020-28935 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by [email protected]
May. 14, 2024
Action Type Old Value New Value -
CVE Modified by [email protected]
Mar. 29, 2023
Action Type Old Value New Value Added Reference https://lists.debian.org/debian-lts-announce/2023/03/msg00024.html [No Types Assigned] -
Modified Analysis by [email protected]
Oct. 12, 2022
Action Type Old Value New Value Changed Reference Type https://lists.debian.org/debian-lts-announce/2021/02/msg00017.html No Types Assigned https://lists.debian.org/debian-lts-announce/2021/02/msg00017.html Mailing List, Third Party Advisory Added CPE Configuration OR *cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* -
CVE Modified by [email protected]
Feb. 12, 2021
Action Type Old Value New Value Added Reference https://lists.debian.org/debian-lts-announce/2021/02/msg00017.html [No Types Assigned] -
Modified Analysis by [email protected]
Feb. 09, 2021
Action Type Old Value New Value Changed Reference Type https://security.gentoo.org/glsa/202101-38 No Types Assigned https://security.gentoo.org/glsa/202101-38 Third Party Advisory -
CVE Modified by [email protected]
Jan. 29, 2021
Action Type Old Value New Value Added Reference https://security.gentoo.org/glsa/202101-38 [No Types Assigned] -
Initial Analysis by [email protected]
Dec. 08, 2020
Action Type Old Value New Value Added CVSS V2 NIST (AV:L/AC:L/Au:N/C:N/I:N/A:P) Added CVSS V3.1 NIST AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Changed Reference Type https://www.nlnetlabs.nl/downloads/nsd/CVE-2020-28935.txt No Types Assigned https://www.nlnetlabs.nl/downloads/nsd/CVE-2020-28935.txt Vendor Advisory Changed Reference Type https://www.nlnetlabs.nl/downloads/unbound/CVE-2020-28935.txt No Types Assigned https://www.nlnetlabs.nl/downloads/unbound/CVE-2020-28935.txt Vendor Advisory Added CWE NIST CWE-59 Added CPE Configuration OR *cpe:2.3:a:nlnetlabs:name_server_daemon:*:*:*:*:*:*:*:* versions up to (excluding) 4.3.4 *cpe:2.3:a:nlnetlabs:unbound:*:*:*:*:*:*:*:* versions up to (excluding) 1.13.0
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2020-28935 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2020-28935
weaknesses.
Exploit Prediction
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days.
0.04 }} 0.00%
score
0.12071
percentile